Process for making a reconstituted tobacco composition

ABSTRACT

A process for manufacturing reconstituted tobacco composition wherein a slurry is created from a solvent, such as water, finely divided tobacco and non-solvent ingredients consisting of ethylhydroxyethyl cellulose and a calcuim or magnesium carbonate. The ethylhydroxyethyl cellulose employed has a gel temperature between 32* and 38*C, an ethoxyl D.S. of 1.2 to 1.6 and a hydroxyethyl M.S. of 0.5 to 1.2. The slurry is mixed and shaped at a temperature below the gellation temperature of the ethylhydroxyethyl cellulose. The ethylhydroxyethyl cellulose added constitutes between 3-15 percent by weight (dry basis) of the reconstituted tobacco composition and in this concentration it provides for improved &#39;&#39;&#39;&#39;burn&#39;&#39;&#39;&#39; characteristics of the composition.

' O I Umted States Patent 1 1- 111 3,795,250 Halter 1 1 Mar. 5, 1974 PROCESS FOR MAKING A 3,288,148 ll/l966 Dctert 131 17 AC x RECONSTITUTED TOBACCO COMPOSITION Primary Examiner-Melvin D. Rein Assistant ExaminerVincent A. Millin [75] Inventor goward Halter Norwalk Attorney, Agent, or Firm-George W. Price; Charles J.

onn. i I Worth [73] Assignee: AMF Incorporated, White Plains,

N. Y. [5 7] ABSTRACT [22] Filed: Aug. 11, 1971 A process for manufacturing reconstituted tobacco composition wherein a slurry is created from a sol- [211 Appl' 170350 vent, such as water, finely divided tobacco and non- Related US. Application Data solvent ingredients consisting of ethylhydroxyethyl [62] Division of Ser. No. 844,652, July 24, I969, Pat. No. Cellulose and a Calcuim or magnesium Carbonate The 3,625,225. ethylhydroxyethyl cellulose employed has a gel tem- Y perature between 32 and 38C, an ethoxyl D8. of 1.2 [52] US. Cl. 131/140 C, 131/17 X. to ln a hy xye hyl MS. of -5 to 1.2. The L511 Int. A24b 3/14 u y is mix a shap d at a t mp ratur l w t s 8 rim of Seareh....'..

131/17'C, 17 AC, 178 AB, l3l/l40, l4OC [56] References Cited UNITED STATES PATENTS 3,613,693 l0/l97l MOtlte 131/140 C gellation temperature of the ethylhydroxyethyl cellulose. The cthylhydroxyethyl cellulose added constitutes between 3-l5 percent by weight (dry basis) of the reconstituted tobacco composition and in this concentration it provides for improved burn characteristics of the composition.

4 Claims, N0 Drawings PROCESS FOR MAKING A RECONSTITUTED TOBACCO COMPOSITION This application is a division of application Ser. No. 844,652, filed July 24, 1969, now US. Pat. No. 3,625,225.

This invention relates to a method of making reconstituted tobacco products with improved burn and taste characteristics. More particularly, this invention relates to the use in said method of a particular grade of ethylhydroxethyl cellulose in reconstituted tobacco compositions and to the novel and beneficial properties which result therefrom.

The usage of reconstituted tobacco products as filler in cigarettes and as wrapper and binder in cigars has increased significantly in recent years. In general, the incentive to use such products in smoking articles is largely economic, since the reconstitution process allows the utilization of tobacco plant portions which were formerly waste because their physical form was unsuitable for manufacturing operations; i.e., tobacco leaf processing fines, tobacco stems, etc. Equally as important for cigar applications are the labor savings which result from the automation of cigar manufacture with reconstituted tobacco sheet material which, in roll form, lends itself to automatic machine dispensation.

However, although the economics of usage of reconstituted tobacco products are unquestionably favorable, the acceptance and usage of such products by manufacturers has not developed as rapidly as would be, anticipated. A major reason'for this retarded rate of usage is that the favorable economics is the deciding factor only if consumer acceptance of smoking articles containing reconstituted tobacco is equal to or better than the corresponding products containing natural tobacco which are being replaced. However, consumer acceptance of these reconstituted tobacco products, especially in cigars has not been equal to that of the natural tobacco counterparts. The major problem areas involve burn and taste, which have been noticeably deficient for reconstituted tobacco products. These problem areas are related, since poor burn characteristics result in different combustion products and are generally accompanied by poorer taste'characteristics. The differences in burn and taste of reconstituted tobacco products as compared to natural tobacco are probably the resultant of the use of non-tobacco ingredients in such products (gums, fibers, insolubilizing agents, humectants, etc. structural differences related to the reconstitution processemployed (paper process, slurry process, etc.) and changes caused by the particular processing conditions employed (drying, losses of volatiles, etc.).

This problem with reconstituted tobacco compositions has been recognized for a number of years. Frankenburg, in US. Pat. No. 2,706,695, issued Apr. 19, i955, attributed the' problem mainly to the watersoluble cellulosic derivatives used as-adhesive binders in such formulations, and proposed the use of siliceous catalysts to alter the combustion characteristics of such formulations. Although some improvements due to such burn catalysts were noted, the experience of the last 14 years has shownthat this approach was far from a complete solution to the problem.

It is interesting to note that F'rankenburg (and his successors in the art) considered the various adhesives and particularly adhesives, falling in the class of cellulose derivatives as being largely responsible for the burn-taste problems encountered in the manufacture of reconstituted tobacco. By and large, this was and is the case; however, we have now discovered a unique cellulose derivative, providing novel function and results opcigar, and may widen to perhaps one thirty-second to one-sixteenth inch when the smoker lays his cigar down for several minutes in an ash tray. With reconstituted cigar wrappers, these width values may be approximately one-sixteenth to one-eighth inch while smoking and one-eighth to three-eighths inches after several minutes without puffing. The appearance of an enlarged burn ring has been found to be particularly objectionable to cigar smokers, and is indicative of poor combustion with resultant adverse taste implications. Burn duration refers to the amount of time that a'lit cigar will remain lit when placed in an ash tray without puffing. With natural-tobacco wrapped cigars, burn duration varys somewhat with cigar shape, and may range from 6 minutes on a cigarillo to about 10 minutes on large cigars. Reconstituted tobacco cigars which go out significantly faster than the conventional nautral tobacco types are annoying to cigar smokers. In fact,

burn durations which are somewhat longer than those for the natural tobacco cigars are considered desirable.

Accordingly, it is an object of this invention to provide a method of making a novel reconstituted tobacco product and a process for making same.

It is a further object of this invention to provide a reconstituted tobacco product which, because of its composition and mode of formation, will have substantially improved and commercially-acceptable burn properties.

It is still a further object of this invention to provide a a method for making reconstituted tobacco composition which, because of itssubstantially improved burn properties, will have significantly improved organoleptic properties as well.

' Additional objectives will become apparent from the description of the invention which follows.

While the invention will be described inconnection I with a method for making tobacco sheet, the burn and taste improvement additive of the present invention may likewise be advantageously used with tobacco in reconstituted compositions with other shapes such as rods, cylinders, plugs, shreds and the like. Accordingly, it will be understood that the invention contemplates also tobacco manufacture of this type.

According to the techniques herein described, when ethylhydroxyethyl cellulose (EHEC) with an ethoxyl D8. is the average number of hydroxyl groups substituted in the cellulose per anhydroglucose unit. M.S. is the average number of moles of reactant combined with the cellulose per anhydroglucose unit. For the alkyl, carboyxalkyl, or acyl derivatives of cellulose, the M.S. is generally greater than the BS. The reason for this is that each time a hydroxyalkyl group is introduced into the cellulose molecule, an additional hydroxyl group is formed which itself is capable of hydroxyalklation. As a result of this, side chains of considerable length may form on the cellulose molecule. The M.S./D5. ratio represents the average length of these side chains. Thus, from the foregoing, it will be seen that the total D8. of a cellulose derivative can be no higher than three, whereas the M.S. may be considerably higher than three, depending on the extent to which side chains are formed.

With a mixed ether such as ethylhydroxethyl cellulose, the ethoxyl content is reported as D.S. since, as noted above, the D8. and M.S. must be the same for this constituent. The hydroxyethyl substituent, on the other hand, is reported as M.S. since addition to side chains is possible in this case.

The two most widely used methods for determining M.S. are the Ziesel-Morgan method and the terminal methyl method. The Zeisel-Morgan method is reported beginning at page 500, v01. 18, 1946, of Industrial and Engineering Chemistry, Analytical Edition. The terminal methyl method is reported by Lemieux and Purves beginning at page 485, vol. 258, 1947, of Canadian Journal of Research. As used herein, the ethoxyl D.S. determined by the terminal methyl method and the hydroxethyl M.S. was determined by the Ziesel-Morgan method. I

Referring to the present invention, other grades of ethylhydroxyethyl cellulose are referred to in the prior art. More specific than the use described in the aforementioned Frankenburg patent is the use of the normal commercial grade of ethylhydroxyethyl cellulose as the adhesive in reconstituted tobacco compositions reported by Rosenberg and Schmidth in U.S. Pat. No. 3,042,552, July 3, 1962. The ethoxyl content of this material is listed by Rosenberg and Schmidt as 17 to 18 percent (D.S. about 0.8),and the hydroxyethyl content at about 17.3 percent (M.S. about 0.9). The ethylhydroxyethyl cellulose used by Rosenberg and Schmidt is different in composition than that of the present invention, which involves an ethoxyl degree of substitution of 1.2 to 1.6 and hydroxyethyl molar substitution of 0.5 to 1.2. The differences are even greater than one might anticipate from the substitution differentials, and are in fact differences in kind, not just in degree. The normal ethylhydroxyethyl cellulose (EHEC) used by Rosenberg and Schmidt will dissolve in water at temperatures up to about 60C. The EHEC of this invention will not dissolve in water if the temperature is over 25C. and, for complete solubilization, the temperature should be below 15C. The Rosenberg and Schmidt EHEC will gel or precipitate from aqueous solution when the temperature is raised to C-70C; the EHEC of the present invention will gel or precipitate from aqueous solution when the temperature is raised to only about 3238C. The Rosenberg and Schmidt EHEC is insoluble in methanol or ethanol or 90 percent isopropanol; the EHEC of the present invention is completely soluble in these solvents. In spite of the fact that both materials are ethylhydroxyethyl celluloses, the differences in substitution between the two grades have resulted in physical and chemical properties for the two grades of gum that are as different from each other as one would expect from adhesives of entirely different classes.

The properties contributed to burn and taste of reconstituted tobacco compositions by the incorporation of the EHEC of the present invention are also radically different from those which are obtained using other carbohydrate, protein or synthetic gums. Furthermore, the burn and taste properties are radically different from those which are obtained with any other cellulose ether and even from other grades of ethylhydroxyethyl cellulose with different levels of substitution. Among the carbohydrate adhesives investigated were animal gums, such as glycogen, plant gums and derivatives, such as cellulose ethers, cellulose ethers, starches, starch ethers, starch esters, amylose, amylopectin and their ester and ether derivatives, locust bean gum, guar gum, gum arabic and related seed gums and plant exudate gums, marine plant gums, such as algins, carrageenans, laminarins and agar, and microbial gums such as' the dextrans, phosphomannans such as USDA B-l459 and B-l428, and the gluconic acid microbial containing gums such as the USDA Y-l409 gums, and water-dispersable protein classes such as animal proteins such as hydrolyzed keratins, egg albumin, and vegetable proteins such as gluten and synthetic gums such as polyvinyl alcohol, polyoxyethylene and poly acrylamide. No significant improvements in burn ring,

burn duration or taste properties were noted with each of these additive types at usage levels of 5-10 percent of the reconstituted tobacco composition.

It is interesting to note that, in a formulation which was constant other than for the type of experimental burn additive, the use of hydroxyethyl cellulose (hydroxyethyl substitution only), ethylcellulose (ethoxyl substitution only) and the normal grade of ethylhydroxyethyl cellulose referred to by Rosenberg and Schmidt (combination of ethoxyl and hydroxyethyl substitution on the same molecule) as burn additives resulted in no significant improvements or trends in the burn and taste results. Yet, the use of the ethylhydroxyethyl cellulose of this invention resulted in significantly different and beneficial burn and taste properties.

According to the techniques herein described substantial burn improvement is obtained when EHEC with an ethoxyl D.S. of 1.2 to 1.6 and a hydroxyethyl M.S. of 0.5 to 1.2 is present at levels of three percent or more of the reconstituted tobacco composition (dry basis). The burn improvement is even more substantial at higher usage levels, but it seems to be never necessary to use more than fifteen percent of this EHEC to achieve optimum burn and taste characteristics.

Investigation of additives other than gums and adhesives were made. Inorganic and organic materials with known burn-acceleration properties in other applications were tested in reconstituted sheet, including inorganic and organic nitrates and peroxides, and calcium or magnesium carbonates which have achieved widespread usage as bum additives in cigarette paper. Although some of these additives (e.g., potassium nitrate) resulted in acceleration of the free burn rate of the reconstituted sheet, when this sheet was converted into a smoking article i.e., by using the reconstituted tobacco sheet as binder and/or wrapper on a cigar, no reduction in the width of the burn ring, no increases in the burn duration, and no taste improvements were noted. Accordingly, it was demonstrated that the problem of burn and taste improvement in shaped'smoking articles containing reconstituted tobacco is complex and involves substantially more than just speeding up the free burn of a reconstitutedtobacco component.

It was found, however, that although the addition of calcium carbonate or magnesium carbonate to a reconstituted tobacco composition had little effect on the significant burn and taste problems of the ultimate smoking article, when the additives were incorporated into compositions which also contained the particular EHEC of the present invention, a synergistic improvement in the burn taste properties of the ultimate smok-- ing article resulted. For example, reconstituted tobacco compositions containing four percent EHEC plus four percent calcium carbonate resulted in somewhat better burn/taste properties in the ultimate smoking article burn/taste improvements achieved with the latter. It

has been found that combinations of two to lO percent of EHEC (ethoxyl D.S. l.2-l .6; hydroxethyl M.S. 0.5-1.2) with two to percent calcium carbonate and/or magnesium carbonate, based on the dry weight of the total reconstituted tobacco composition, results in optimum burn and taste properties for the various smoking articles of interest. The optimum combination for each type of reconstituted sheet and for each type of smoking article may be determined empirically by those skilled in the art.

it should be noted that the burn and taste advantages associated with the use of the particular EHEC of this invention are due to the degree of substitution of the ethoxyl and hydroxyethyl substituents, with no significant effect of the viscosity of gum on these properties. Of course, the higher the viscosity of the EHEC, the more it will function as an adhesive and the more it will contribute to the strength of the reconstituted tobacco product. However, even the lowest viscosity and lowest molecular weight grades of EHEC, which are poor filmformers and do not function to any extent as adhesives, will contribute the burn and taste advantages described above.

The following are examples of the present invention as employed in the manufacture of reconstituted tobacco sheet:

EXAMPLE I and five parts (dry basis) of a percent dispersion of minus 120 mesh Wisconsin leaf tobacco dust. The tobacco slurry is then prepared and cast, also in a conventional manner, into a shaped form, namely a sheet, at a thickness such that the tobacco slurry film, after drying, will weight 3 grams per square foot. The cast tobacco slurry film is dried at -l0OC.

The resultant reconstituted tobacco sheet containing 13.9 percent ethylhydroxethyl cellulose (dry basis) was used as a wrapper on a perfecto-shaped large cigar which also contained a natural Wisconsin tobacco leaf binder and chopped Puerto Rican filler. The cigar, on combustion, exhibited a burn ring only about one sixtyfourth inch in width while smoking, and only one thirtysecond inch in width when allowed to rest in an ashtray for 4 minutes without pufffing. The burn duration when the cigar was not being puffed was 14 minutes before the cigar self-extinguished. The taste characteristic of the cigar was considered by a panel of smoking connoisseurs to be comparable to that of a natural wrapped control cigar. For comparison, the same cigar with a natural Connecticut shade wrapper had the same width of burn rings while smoking and upon resting in an ashtray for 4 minutes. The burn duration was 12 minutes before the cigar self-extinguished.

EXAMPLE la EXAMPLE ll A tobacco slurry is prepared by first adding one part (dry basis) of a 3.2 percent dispersion of refined sulfite pulp to 0.6 parts (dry basis) of a two percent aqueous dispersion of guar gum. To the resultant dispersion is added 0.4 parts (dry basis) of a two percent .aqueous dispersion of ethylhydroxyethyl cellulose with an ethoxyl D8. of 1.6, a hydroxyethyl M.S. of 1.2 and a viscosity of 300 cps, 0.2 parts (dry basis) of a 40 percent aqueous solution of glyoxal and 10 parts (dry basis) of a 20 percent dispersion of minus I20 mesh Wisconsin leaf tobacco dust. The tobacco slurry is cast and dried as in Example 1, and was evaluated as wrapper on a cigar comparable to that employed in Example I. The cigar exhibited a burn ring one thirty-second inch while smoking and one-sixteenth inch in width when allowed to rest in an ashtray for 4 minutes. The burn duration when the cigar was not being puffed was 12 minutes before the cigar self-extinguished. The taste characteristic was considered comparable in quality to that of a natural tobacco wrapped cigar counterpart by a panel of cigar smokers.

EXAMPLE I v A tobacco slurry is prepared as described in Example II. To this slurry is added with agitation 0.6 parts of a 10 percent aqueous suspension of calcium carbonate with an average particle size of about 0.5 microns. The resultant slurryis deareated, cast and dried as in Example II, and was evaluated as wrapper on a cigar comparable to that employed in Examples l and I]. The cigar exhibited a burn ring one sixty-fourth inch in width while smoking, one thirty-second inch in width when allowed to rest in an ashtray for 4 minutes. and a burn duration of 16 minutes when the cigar was not being puffed.

The three examples given above are illustrative only of the application of the present invention to the production of reconstituted tobacco product. The prior art is complete with literature describing various methods of tobacco preparation, slurry formation, casting and drying. None of these prior art techniques is critical to the application of the present invention, and the present description omits lengthy explanation of apparata and methods relating thereto for the sake of brevity.

It will thus be observed that novel, reconstituted tobacco product is obtained within the scope of the objectives set forth previously.

What is claimed is:

l. The method of manufacturing a reconstituted tobacco product having improved properties comprising forming a slurry from a solvent, finely divided tobacco and nonsolvent ingredients in which ethylhydroxyethyl cellulose is added in such an amount that the ethylhydroxyethyl cellulose constitutes 3-15 percent by weight (dry basis) of the said product, having a gel temperature of about 32 to 38C with an ethoxyl D.S. of 1.2 to 1.6 and a hydroxyethyl M.S. of0.5 to L2, mixing and shaping said slurry at a temperature below the gellation temperature of said ethylhydroxyethyl cellulose and subsequently drying said shaped slurry to a predetermined solvent content.

2. The method according to claim 1 wherein said solvent is water.

3. The method according to claim 1 wherein said ethylhydroxyethyl cellulose is mixed with said solvent prior to dispersion with said tobacco.

4. The method according to claim 1 wherein said ethylhydroxyethyl cellulose comprises about 10 percent by weight of the non-solvent ingredients of said composition and including the step of adding to said slurry 2 to 10 percent by weight of the non-solvent ingredients of a carbonate selected from the group consisting of calcium and magnesium carbonates. 

2. The method according to claim 1 wherein said solvent is water.
 3. The method according to claim 1 wherein said ethylhydroxyethyl cellulose is mixed with said solvent prior to dispersion with said tobacco.
 4. The method according to claim 1 wherein said ethylhydroxyethyl cellulose comprises about 10 percent by weight of the non-solvent ingredients of said composition and including the step of adding to said slurry 2 to 10 percent by weight of the non-solvent ingredients of a carbonate selected from the group consisting of calcium and magnesium carbonates. 